US president-elect Donald Trump has vowed to step back from running his global business empire to avoid conflicts of interest but gave few immediate details as concern over his dual role mounts ahead of his Jan 20 inauguration.

Trump, a real estate magnate who owns hotels and golf resorts from Panama to Scotland, said on Wednesday he would spell out at a Dec 15 news conference how he will separate himself "in total" from his worldwide business holdings, which include a winery, modeling agency and a range of other businesses.

After Trump won the Nov 8 election, his company, the Trump Organization, had said it was looking at new business structures with the goal of transferring control to Donald Trump Jr., Ivanka Trump and Eric Trump - three of his adult children who are involved with the company.

Trump gave few details in a series of early morning tweets but said that "legal documents are being crafted which take me completely out of business operations" and that his children would attend the news conference.

Critics have raised questions about the role of Trump's children, who are on the executive committee of his White House transition team. His daughter Ivanka joined a telephone call her father had with Argentine President Mauricio Macri earlier this month and attended a meeting with Japanese Prime Minister Shinzo Abe, creating concerns about possible conflicts of interest.